U.S. patent application number 15/655092 was filed with the patent office on 2019-01-24 for cryotherapy device for the treatment of cervical precancerous lesions.
This patent application is currently assigned to Jhpiego Corporation. The applicant listed for this patent is Shuja T. Dawood, Enriquito Lu, John-William Sidhom, Marton Varady. Invention is credited to Shuja T. Dawood, Enriquito Lu, John-William Sidhom, Marton Varady.
Application Number | 20190021777 15/655092 |
Document ID | / |
Family ID | 65014587 |
Filed Date | 2019-01-24 |
United States Patent
Application |
20190021777 |
Kind Code |
A1 |
Varady; Marton ; et
al. |
January 24, 2019 |
Cryotherapy Device For The Treatment of Cervical Precancerous
Lesions
Abstract
A device for providing a patient with a cryotherapy process that
is directed to the ablation of a lesion on the patient, includes:
(a) a piping assembly adapted to create a spray of carbon dioxide
snow, (b) a snow horn having a pressure relief means and a boundary
wall, (c) a tubular applicator with ends between which extends an
interior wall that has an interior diameter that increases in value
between these ends, (d) an applicator tip with a metal portion and
adapted to allow it to connect to the applicator's distal end, and
(e) a push rod having a distal end with a base to which is attached
an anchor.
Inventors: |
Varady; Marton; (Baltimore,
MD) ; Dawood; Shuja T.; (Santa Clara, CA) ;
Sidhom; John-William; (Westfield, NJ) ; Lu;
Enriquito; (Baltimore, MD) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Varady; Marton
Dawood; Shuja T.
Sidhom; John-William
Lu; Enriquito |
Baltimore
Santa Clara
Westfield
Baltimore |
MD
CA
NJ
MD |
US
US
US
US |
|
|
Assignee: |
Jhpiego Corporation
Baltimore
MD
|
Family ID: |
65014587 |
Appl. No.: |
15/655092 |
Filed: |
July 20, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B 18/0218 20130101;
A61B 18/02 20130101; A61B 2018/00559 20130101; A61B 2018/0231
20130101; A61B 2018/00577 20130101; A61B 2018/00583 20130101; A61B
2018/0212 20130101 |
International
Class: |
A61B 18/02 20060101
A61B018/02 |
Claims
1. A device that is adapted to connect to the outlet of a
pressurized tank containing liquid carbon dioxide for providing a
patient with cryotherapy process that is directed to the ablation
of a lesion on said patient, said device comprising: a piping
assembly having a configuration that includes a distal end adapted
to connect to said pressurized tank outlet and a proximal end with
a nozzle adapted to create a spray of carbon dioxide snow as a
result of the freezing of said liquid carbon dioxide upon its
exhaustion from said piping assembly, a tubular, snow horn having a
configuration that includes a distal end, adapted to to connect to
said piping assembly proximal end, and a proximal end, a boundary
wall extending between said ends and enclosing the interior region
of said snow horn, and wherein said snow horn distal end having a
snow horn nut and pressure relief means, a tubular applicator
having a distal end, adapted to temporarily connect to said snow
horn proximal end, and a proximal end and an interior wall
enclosing the interior region of said tubular applicator, and
wherein said interior wall having an interior diameter that
increases in value from the proximal end to the distal end of said
applicator, and wherein said interior wall having a plurality of
vent holes, an applicator tip having an inner surface and an outer
surface that includes a metal portion and a configuration adapted
to allow said applicator tip to connect to said applicator distal
end during said cryotherapy process and to allow said metal portion
of said outer surface of said applicator tip to come into contact
with said patient, and a push rod having a distal end and a
proximal end, and a base attached to said push rod distal end and
wherein said base includes an anchor.
2. The device as recited in claim 1, further comprising: a handle
having a barrel, a grip, a thumb-operated trigger and a drive
system adapted to control the movement of said push rod during said
cryotherapy process.
3. The device as recited in claim 1, further comprising: a wind
knob situated on said handle and adapted to control the movement of
said push rod during said process of collecting snow in said
tubular applicator.
4. The device as recited in claim 2, wherein: said handle barrel
has a centerline and said handle grip has a centerline and said
centerlines intersect so that the enclosed angle formed by said
intersecting centerlines is in the range of 10-20 degrees.
5. The device as recited in claim 3, wherein: said handle barrel
has a centerline and said handle grip has a centerline and said
centerlines intersect so that the enclosed angle formed by said
intersecting centerlines is in the range of 10-20 degrees.
6. The device as recited in claim 1, wherein: the amount of
increase in said interior diameter of said inner tube between said
inner tube ends when divided by the length of said inner tube is in
the range of 0.4 to 1.6 percent.
7. The device as recited in claim 2, wherein: the amount of
increase in said interior diameter of said inner tube between said
inner tube ends when divided by the length of said inner tube is in
the range of 0.4 to 1.6 percent.
8. The device as recited in claim 3, wherein: the amount of
increase in said interior diameter of said inner tube between said
inner tube ends when divided by the length of said inner tube is in
the range of 0.4 to 1.6 percent.
9. The device as recited in claim 4, wherein: the amount of
increase in said interior diameter of said inner tube between said
inner tube ends when divided by the length of said inner tube is in
the range of 0.4 to 1.6 percent.
10. The device as recited in claim 5, wherein: the amount of
increase in said interior diameter of said inner tube between said
inner tube ends when divided by the length of said inner tube is in
the range of 0.4 to 1.6 percent.
11. The device as recited in claim 1, wherein: said tubular snow
horn, tubular applicator and applicator tip configurations are all
further adapted for when said patient is a human.
12. The device as recited in claim 2, wherein: said tubular snow
horn, tubular applicator and applicator tip configurations are all
further adapted for when said patient is a human.
13. The device as recited in claim 3, wherein: said tubular snow
horn, tubular applicator and applicator tip configurations are all
further adapted for when said patient is a human.
14. The device as recited in claim 5, wherein: said tubular snow
horn, tubular applicator and applicator tip configurations are all
further adapted for when said patient is a human.
15. The device as recited in claim 7, wherein: said tubular snow
horn, tubular applicator and applicator tip configurations are all
further adapted for when said patient is a human.
16. The device as recited in claim 1, wherein: said tubular snow
horn, tubular applicator and applicator tip configurations are all
further adapted for a cryotherapy process that is directed to the
removal of cervical, precancerous lesions for the prevention of
cervical cancer.
17. The device as recited in claim 2, wherein: said tubular snow
horn, tubular applicator and applicator tip configurations are all
further adapted for a cryotherapy process that is directed to the
removal of cervical, precancerous lesions for the prevention of
cervical cancer.
18. The device as recited in claim 3, wherein: said tubular snow
horn, tubular applicator and applicator tip configurations are all
further adapted for a cryotherapy process that is directed to the
removal of cervical, precancerous lesions for the prevention of
cervical cancer.
19. The device as recited in claim 5, wherein: said tubular snow
horn, tubular applicator and applicator tip configurations are all
further adapted for a cryotherapy process that is directed to the
removal of cervical, precancerous lesions for the prevention of
cervical cancer.
20. The device as recited in claim 7, wherein: said tubular snow
horn, tubular applicator and applicator tip configurations are all
further adapted for a cryotherapy process that is directed to the
removal of cervical, precancerous lesions for the prevention of
cervical cancer.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This is a continuation-in-part, patent application that
claims the priority and benefits of U.S. patent application Ser.
No. 13/898,962, filed May 21, 2013 by the present inventors and
entitled "CRYOTHERAPY DEVICE AND METHOD FOR THE TREATMENT OF
CERVICAL PRECANCEROUS LESIONS" and for which U.S. Pat. No.
9,717,546 will issue on Aug. 1, 2017. The teachings of this parent
application are incorporated herein by reference to the extent that
they do not conflict with the teaching herein.
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0002] The present invention relates generally to surgery devices
and methods. More particularly, the present invention relates to a
cryotherapy device and method to treat, destroy or ablate a
patient's abnormal tissues or lesions, e.g., for the ablation of
cervical, precancerous lesions to prevent cervical cancer.
2. Description of the Related Art
[0003] Cervical cancer is the third most common cancer in the
world. Moreover, eighty percent of all cervical cancer cases occur
in the developing world. With approximately 500,000 new cases each
year, cervical cancer is responsible for over 250,000 deaths per
year, making it the second leading cause of death in developing
countries. Many of these deaths are women in their late 30s and
early 40s, thus compromising the health and well-being of the
surrounding family. Indeed, this is especially true for the
children of these women, who often fall behind in their education
and may be abandoned, without a mother.
[0004] While steps, such as annual PAP smears and other
interventional methods, have been taken to eradicate cervical
cancer in the developing world, cervical cancer still remains a
large burden for these countries. Its prevalence in the developing
world can in large part be attributed to a lack of appropriated
technologies for screening and treatment.
[0005] A "single visit" approach has been developed and includes a
screening by visual inspection with acetic acid and a
point-of-diagnosis cryotherapy treatment. This approach for
screening and treatment has provided a safe, acceptable, and
feasible option in low-resource settings.
[0006] Cryotherapy includes freezing the abnormal cervical tissue
with a coolant such as carbon dioxide, CO.sub.2, and has been used
for over forty years to treat cervical dysplasia. This process uses
what is called a "double freeze procedure." One freezes the cervix
for three minutes and then allows it to thaw for five minutes, then
it is frozen again for an additional three minutes. This procedure
maximizes the amount of tissue that is frozen more so than just
doing one extra-long freeze because the frozen tissue becomes more
thermally conductive after the first freeze so the second freeze
penetrates quicker and subsequently deeper into the affected
tissue.
[0007] Cryotherapy is the leading method for the ablation of
cervical precancerous lesions for the prevention of cervical
cancer, especially in the developing world. Despite proven efficacy
of cryotherapy as a mode of ablating precancerous lesions, the
current state of the art used to facilitate cryotherapy is not
sufficiently designed for widespread and reliable use in the
developing world.
[0008] While this single visit approach or "screen and treat"
program has been shown to be effective in prevention of cervical
cancer, there still remains a hurdle to scaling up such a program
for widespread impact. While cryotherapy using CO.sub.2 has been
shown to be safe and effective, even in the hands of low-level
health care workers, the equipment is not necessarily suitable to
be widely dispersed. Indeed, cryotherapy tools can be expensive,
technically complex, lacking portability, and difficult to repair
in the field.
[0009] Currently, the developing world utilizes cryoguns, see, for
example, U.S. Pat. No. 4,377,168 which discloses expanding
pressurized CO.sub.2 (or N.sub.2O in some instances when a country
or program can afford the added expense of the N.sub.2O) against a
thermally conductive tip. The expansion of the CO2 in this closed
system creates a temperature of approximately -50 to -70 degrees C.
on the surface of the tip which is in contact with a lesion.
[0010] With carbonated beverage manufacturers being widely
dispersed in the developing world, and often using carbon dioxide
to produce their carbonated beverages, carbon dioxide manufacturers
are also widely dispersed in the developing world. This has led to
cryoablation being conducted with carbon dioxide as the primary
source of coolant.
[0011] The current design of cryotherapy tools suffers from several
flaws when utilized with carbon dioxide tanks, including: water
vapor leaving the tank causes tip blockages, non-medical grade
carbon dioxide may have particulates, which cause tip blockages,
and a pressure drop may occur in the cylinder through the cooling
process during extended use which results in warmer and less
effective tip temperatures.
[0012] Additionally, the equipment was never originally designed
for use within the extreme conditions of the developing world where
there are high volumes of ablations along with environmental abuse
of the product. First, the tips on the current cryotherapy tools
are manufactured with gold or chrome plating, which not only makes
the tip expensive, at approximately three hundred dollars per tip,
but these tips also suffer from corrosion from the chlorine
disinfection method--the widely available method for sterilization
in the developing world.
[0013] Improper cleaning and storage of these tips also leads to
clogs, requiring replacement. Additionally, the overall cost of the
equipment is around thirteen hundred to two thousand dollars per
device. Moreover, with the complexity of this equipment's
engineering design, there is a lack of repair knowledge and backup
parts when the equipment breaks down. Unfortunately, when the
cryotherapy equipment malfunctions in the field, the device becomes
unused and is rarely capable of being easily fixed.
[0014] Finally, the amount of carbon dioxide required per treatment
limits the portability of the device. A tank containing 50 lbs of
CO.sub.2, weighs approximately 160 lbs total, and treats only about
10 to 15 patients. These large tanks are therefore difficult to
transport to the rural areas where women need to be screened and
treated, either in the context of health centers, mobile health
vehicles or organized screen & treat camps. Therefore, these
characteristics of current cryotherapy equipment prohibit its
massive scale-up for widespread impact on reducing the burden of
cervical cancer.
[0015] It would therefore be advantageous to provide a device and
method that could safely, effectively, and in a low-cost manner
treat, destroy or ablate cervical, precancerous lesions in order to
prevent cervical cancer.
SUMMARY OF THE INVENTION
[0016] Recognizing the need in emerging nations for the development
of improved cryotherapy techniques, the present invention is
generally directed to satisfying this need. The present invention's
method of treatment or process for providing cryotherapy ablation
utilizes a pressurized tank of a low-temperature liquid as its
source for the low-temperature, thermal reservoir that is needed to
conduct by this process.
[0017] A preferred embodiment of the present invention takes the
form of a device, that is adapted to connect to the outlet of a
tank that is pressurized and contains liquid carbon dioxide for
providing a patient with a cryotherapy process that is directed to
the ablation of lesions, includes: (a) a piping assembly having a
configuration that includes a distal end, adapted to connect to
said pressurized tank outlet, and a proximal end with a nozzle
adapted to create a spray of carbon dioxide snow as a result of the
freezing of the liquid carbon dioxide upon its exhaustion from the
piping assembly, (b) a tubular, snow horn having a configuration
that includes a distal end, adapted to connect to the piping
assembly proximal end, and a proximal end, a boundary wall
extending between the ends and enclosing the snow horn's interior
region, and wherein the snow horn distal end includes a snow horn
nut and pressure relief means, (c) a tubular applicator having a
distal end, adapted to temporarily connect to the snow horn
proximal end, and a proximal end and an interior wall extending
between these ends and enclosing the applicator's interior region,
and wherein this interior wall has an interior diameter that
increases in value from the proximal end to the distal end of the
applicator, and wherein this interior wall has a plurality of vent
holes, (d) an applicator tip having an inner surface and an outer
surface that includes a metal portion and a configuration adapted
to allow the applicator tip to connect to the applicator's distal
end during process of providing cryotherapy ablation, and (e) a
push rod having a distal end and a proximal end and a base attached
to the push rod distal end and wherein this base includes an
anchor.
[0018] A first variant of this preferred embodiment further
includes a handle having a barrel, a grip, a thumb-operated trigger
and a drive system adapted to control the movement of the push rod
during the process of providing said cryotherapy ablation.
[0019] A second variant of this preferred embodiment further
includes a wind knob situated on the handle and adapted to control
the movement of the push rod during the process of collecting snow
in the tubular applicator.
[0020] A third variant of this preferred embodiment is adapted so
that the handle barrel has a centerline and the handle grip has a
centerline, and these centerlines intersect so that the enclosed
angle formed by these intersecting centerlines is in the range of
10-20 degrees.
[0021] A fourth variant of this preferred embodiment is adapted so
that the amount of increase in the diameter of applicator's
interior wall between its ends when divided by the length between
these ends is in the range of 0.4 to 1.6 percent.
[0022] Another preferred embodiment of the present invention is
that in which the configurations of the piping assembly, tubular
snow horn, tubular applicator and applicator tip configurations are
all further adapted for a cryotherapy process that is directed to
the removal of cervical, precancerous lesions for the prevention of
cervical cancer.
[0023] Thus, there has been summarized above (rather broadly and
understanding that there are other preferred embodiments which have
not been summarized above) the present invention in order that the
detailed description that follows may be better understood and
appreciated.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] FIG. 1(a) is a perspective view of the piping assembly of
the present invention.
[0025] FIG. 1(b) is a perspective view of the snow horn of the
present invention.
[0026] FIG. 1(c) is a perspective view of the, assembled and filled
with CO.sub.2 snow, applicator, applicator tip, push rod, spring
and handle of the present invention.
[0027] FIG. 2 is an exploded, perspective view of the elements of
the present invention shown in FIG. 1(c).
[0028] FIG. 3 is a perspective view of an applicator tip that is
suitable for use in the present invention.
[0029] FIG. 4 is a perspective view of the anchor that is situated
on the distal end of the push rod of the present invention.
[0030] FIG. 5 is a side view of a snow horn that is suitable for
use in the present invention.
[0031] FIG. 6 is a side view of a hollow tubular applicator that is
suitable for use in the present invention.
[0032] FIG. 7 is a cross-sectional view of the hollow tubular
applicator shown in FIG. 6.
[0033] FIG. 8 is a right side, perspective views of a handle that
is suitable for use in the present invention.
[0034] FIG. 9 is a left side, perspective views of a handle that is
suitable for use in the present invention.
[0035] FIG. 10 is a cross-sectional view of the interior of the
handle shown in FIGS. 8-9.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0036] Before explaining at least one embodiment of the present
invention in detail, it is to be understood that the invention is
not limited in its application to the details of construction and
to the arrangements of the components or elements set forth in the
following description or illustrated in the drawings. This
invention is capable of being practiced and carried out in various
ways. Therefore, it is to be understood that the present invention
is not to be limited to the specific embodiment disclosed herein,
and that its many variants are intended to be included within the
scope of the appended claims. Also, it is to be understood that the
phraseology and terminology employed herein are for the purpose of
description and should not be regarded as limiting. In the
accompanying drawings, like numbers refer to like elements
throughout.
[0037] A preferred embodiment in accordance with the present
invention 1 provides an apparatus or device and method that
extracts heat from a warmer medium or material such as human or
animal tissue. As shown in this application's figures, the
embodiment of the present invention that is shown there utilizes
cryotherapy to treat, destroy or ablate a patient's abnormal
tissues or lesions, e.g., when the patient is a member of the
animal species, which includes female humans for the ablation of
cervical, precancerous lesions for the prevention of cervical
cancer. The device includes an auxiliary piping assembly 10 that is
configured to be connected to the typically horizontally-directed
outlet of a pressurized, carbon dioxide tank in the bottom of which
resides liquid carbon dioxide, CO.sub.2, or other suitable fluid
that freezes at a comparatively low temperature (i.e., the phase
diagram for CO.sub.2 reveals that it can, when it is under
pressures in the range of approximately 5-100 atmospheres, only
pass from a liquid to a solid state when its temperature is also
below approximately minus 60 degrees Centigrade--we define herein
fluids that can remain in a liquid state at such elevated pressures
and when approaching such reduced temperatures as low-temperature
liquids which upon freezing yield low-temperature snows).
[0038] The purpose of this piping assembly and its configuration is
adapted to yield the proper flow conditions for the beginning of
the creation of the CO.sub.2 snow or "dry ice" from the distal end
of the piping assembly when the pressurized tank of carbon dioxide
is allowed to exhaust through the piping assembly at operating
pressures in the range of 750-850 psig and the CO.sub.2 freezes as
it exits the assembly. See U.S. Pat. No. 6,543,251 and European
Patent Number (EP) 1,046,614B1 for background technology related to
the creation of CO.sub.2 snow.
[0039] One variant for the configuration of this piping assembly 10
includes a distal end 12 that has an adapter 14 which allows the
piping assembly to be connected and firmly affixed to the tank's
outlet, while also reducing the diameter of the pipe through which
the exhaust is flowing. See FIG. 1(a).
[0040] A pressure gauge 16 that is sized to measure and read
pressures up to approximately 700-1,000 psig is included in this
piping assembly so as to check to ensure that the tank pressure is
adequate to support the creation of CO.sub.2 snow. It also includes
a valve 18 that regulates flow through the piping assembly. A
ninety degree elbow 20 that is used to redirect the normal
direction of the flow from the tank from being horizontal to
vertical, and a proximal end 22 to which is attached a nozzle 24
whose outlet or orifice 24a diameter is critical to the efficient
operation of the piping assembly and it's on-demand, capability to
begin the creation of CO.sub.2 snow.
[0041] A preferred variant of this piping assembly's distal end has
the diameter of the pipe to which the nozzle connects being 1/8 of
an inch and the diameter of the nozzle's orifice 24a being in the
range of 0.005-0.050 inches, with a preferred value of 0.016
inches. Downstream from this nozzle and its orifice 24a is a snow
horn 26 which has a boundary wall 26c and a configuration adapted
to create the final flow conditions for the collection of CO.sub.2
snow having a desired density. Alternatively, the snow horn has a
configuration adapted to create the proper flow conditions at the
snow horn's proximal end so as to enable a prescribed mass of the
snow of a desired density to be collected in a specified period of
time. See FIG. 1(b). This snow horn has a distal end 26a that has a
configuration that allows it to be locked to a comparable fitting
(e.g., 1/8 inch NPT tap) on the proximal end 22 of the piping
assembly. The proximal end 26b of this snow horn has a special
fitting or coupling 28 that allows for it to be easily connected to
and disconnected from the distal end 34 of the device's applicator
30. This coupling 28 is also configured as the element of the
device which has the least structural strength. The purpose of this
is to ensure that the device will break apart at this coupling
during a situation in which an accident were to occur and an excess
CO.sub.2 pressure were to be applied to the device. Typical snow
horn dimensions are an outer diameter of approximately 0.50 inches,
a wall thickness of approximately 0.125 inches and lengths in the
range of 7-9 inches, with a preferred length of 8 inches.
[0042] The CO.sub.2 snow's desired density is chosen so that the
mass of CO.sub.2 snow collected is sufficient to provide the needed
low temperature reservoir while also allowing the scale of the
device to be such that it is appropriate for the desired
cryotherapy procedure. Experimentation has shown that a CO.sub.2
snow density in the range of 8-11 g/in.sup.3 allows the required
mass of snow to be in the range of 8-10 g for a normal preventive,
ablation of cervical, precancerous lesions procedure.
[0043] The present invention also includes a hollow, tubular
applicator 30 which has proximal 32 and distal 34 ends. As its name
implies, this part of the present invention is used by a health
care provider to help precisely locate the point/s on a patient
where the invention's cryotherapy will be applied. This applicator
30 has a configuration that is adapted to collect and temporarily
store in its interior 36 and proximate its distal end the mass 6 of
CO.sub.2 snow that is required (i.e., sufficient to allow the mass
of collected snow to serve as the low temperature thermal reservoir
for the device after the applicator's distal end has been
disconnected from the snow horn and the applicator's tip attached
so the applicator and its tip together can be used to perform a
cryotherapy ablation).
[0044] See FIG. 1(c). See also FIG. 2 which is an exploded,
perspective view of the elements of the present invention that are
shown in FIG. 1(c).
[0045] A flow-through fitting 40 is provided at the applicator's
distal end that is configured to allow for, among other things, the
attachment and detachment of the applicator's distal end to and
from the coupling 28 on the distal end of the snow horn during the
part of the process in which the applicator is filled with CO.sub.2
snow. This same fitting 40, upon being decoupled from the snow
horn, is also configured to allow it to be used for attaching to
the applicator's distal end an especially designed applicator cap
or tip 50 which is the part of the device that actually comes into
contact with a patient's body where it is desired to freeze and
ablate targeted tissues or cells.
[0046] The proximal end 32 of the applicator has an opening 38 that
allows access to the applicator's interior from this proximal end.
This opening allows for the introduction of a means for advancing
60 any CO.sub.2 snow that may accumulate in the applicator. For the
embodiment shown in FIGS. 1(c) and 2, this means includes a base 66
at the distal 64 end of a retractable, push rod or plunger 60 that
can be inserted to different distances into the applicator. The
outer boundaries of this base have a configuration that is adapted
to allow them to provide a sliding seal against the applicator's
interior wall 42. The distal portion of this base, when the push
rod is adjustably inserted into the applicator, thus forms the
furthest boundary at which CO.sub.2 snow may accumulate in the
applicator. The wall 42 of the applicator is also provided with a
number of vent holes 44 by which gases can be vented during the
CO.sub.2 snow filling process.
[0047] In the alternate venting pattern, channels running parallel
to the axis of the applicator allow gas venting to the atmosphere
at both the proximal 32 and distal 34 ends of the applicator. The
opening to each of the channels is sufficiently small such that the
particles of snow do not coagulate in this region in such a way as
to block the channels. The channels may also serve to vent the
sublimating gas during a cryotherapy treatment procedure and
thereby prevent accumulation of the sublimate in the vaginal cavity
which inhibits the device operator's ability to see the distal end
of the applicator.
[0048] The exact dimensions of such an applicator will obviously be
a function of the type of cryotherapy procedure that is desired to
be performed using the present invention. For a normal preventive,
ablation of cervical, precancerous lesions procedure, typical
dimensions for this applicator are: outer diameter=5/8 inch, wall
thickness= 1/16 inch when polycarbonate extruded tubing is being
used as the material from which to fabricate the tube, length in
the range of 6-8 inches, vent holes: diameters in the range of
0.02-0.03 inches and 15-20 in number and spaced at 0.25 inch
intervals along the length of the tube. For an applicator sized in
this manner, typical snow horn dimensions would then be: length=7-9
inches, inside tube diameter=3/8 inch and where it may be
fabricated from an assortment of plastics, including polycarbonate,
acrylic, polysulfone, ABS, acetal copolymer, or polypropelene.
[0049] Once the applicator is sufficiently filled with CO.sub.2
snow, the applicator is disconnected from the snow horn and an
applicator cap or tip 50 is attached to the fitting 40 on the
applicator's distal end 34. During a cryotherapy treatment process,
the mass or plug 6 of CO.sub.2 snow must be continually pressed up
against the inner side 52 of the applicator cap to ensure that the
plug has good thermal contact with the applicator cap 50. An
appropriately sized spring or other suitable biasing means 70 is
fitted around the push rod and travels along with the push rod and
up into the applicator's interior. The distal end 72 of this spring
presses against the back side of the base of the applicator while
its proximal end 74 rest against a portion of an especially
configured handle 80 that has a configuration adapted to allow the
handle to be hand-operated to control the positioning of the
applicator's tip 50 and either lock in position or incrementally
advance the push rod and the plug of CO.sub.2 snow.
[0050] Since, during a cryotherapy procedure, the plug 6 of
CO.sub.2 snow is slowly moving towards the distal end of the
applicator, the interior wall 42 of the applicator near its distal
end has been provided with a slight outward taper in order to aid
the forward movement of this plug. For a normal preventive,
ablation of cervical, precancerous lesions procedure, and
consistent with the typical dimensions previously given for an
applicator, a typical taper is in the range of 0.5-6.0 percent, or
more preferably in the range of 1-3 percent.
[0051] The handle 80 of the present invention is of a two-piece
82a, 82b construction and contains an opening 84 in the front face
86 of the handle and into which the proximal end 32 of the
applicator is press fitted. This opening extends all the way
through the handle and therefore allows the proximal end 62 of the
push rod to extend from the rear face 88 of the handle. A
spring-loaded trigger 90 is affixed to the handle and is configured
such that a boundary edge 92 of the trigger interacts with grooves
60a on the push rod to provide the handle with its ability to
incrementally advance or lock the push rod's position relative to
the handle. The retraction of the push rod is handled manually (for
example, to allow for the filling of the distal end of the
applicator with CO.sub.2 snow), i.e., the handle's trigger is
pulled backward to release the push rod while the proximal end of
the push rod is grasped in the free hand of the one who is holding
the device's handle and pulled backward to retract the push
rod.
[0052] This device's applicator cap or tip 50 has a configuration
adapted to allow it to be attached to and detached from the fitting
40 applicator's distal end and provide good thermal transfer
through it since it is this tip that comes into contact with a
patient and therefore needs an adequate rate of low-temperature
thermal transfer from the mass of collected snow to the patient for
the cryotherapy ablation process to be successful. This capability
is provided by forming its outer surface 54 which comes into
contact with a patient from metal while the remainder of the tip is
normally formed from plastic. FIG. 3 shows an exploded perspective
view of such an applicator tip where an intermediate ring 56 is
used to help attaching the taps 54a of the metal outer surface to
the ring 56 and it to the tip's connector 58 which has protrusions
58a on either side of it that aid in gripping the applicator tip.
The intermediate ring 56 is then attached, usually via gluing, to
the tip's connector 58.
[0053] The method or steps for using the present invention include:
[0054] 1. Attaching the piping assembly to a siphoned CO.sub.2 tank
such that it's distal end points downward (note: if using a
non-siphoned CO.sub.2 tank, the distal end should point upward when
the tank is valve side up), [0055] 2. Opening the outside packaging
of the high level disinfected and/or sterilized components (i.e.,
snow horn, applicator, push rod, applicator cap, spring, handle) of
the present invention without touching the interior of the
wrapping. [0056] 3. Wiping down a small work surface on which to
place the components that are to assembled to make the handle with
a solution of 70% or 99% isopropyl alcohol [0057] 4. Wiping down
the assembled handle and the on/off lever of the piping assembly
with a solution of 70 or 90% isopropyl alcohol, [0058] 5. Putting
on sterile or disinfected gloves, [0059] 6. Removing the snow horn
and threading or attaching it's distal end to the proximal end of
the piping assembly until they are hand-tight, locked together,
[0060] 7. Removing an applicator and inserting its proximal end
into the opening in the handle's front face, [0061] 8. Dropping the
spring into the applicator, [0062] 9. Placing the push rod into the
applicator and spring with its proximal end going into and through
the handle (squeeze the trigger to allow the push rod to pass all
the way through), pulling back on the rod's proximal end once it is
through the handle (rather than pushing from the rod's distal end)
to completely retract the push rod and then releasing the trigger
(don't release the push rod until trigger is completely locked into
the grooves of the push rod), [0063] 10. Sliding the assembled
handle and applicator into the snow horn, the tabs on the
applicator's distal end go into the coupling on the snow horn's
proximal end (a click will indicate that it is fully seated),
[0064] 11. On the piping assembly, turning the on/off valve to on;
keeping it on until the CO.sub.2 snow is visible above the fitting
on the end of the snow horn--then, turning the valve to off, [0065]
12. Disconnecting the assembled handle and applicator from the snow
horn by sliding it out the way it went in, [0066] 13. Sliding the
applicator cap onto the distal end of the applicator and twisting
it to lock it in place, the device is now ready to perform a
freeze, [0067] 14. To freeze, simply squeeze the trigger, there
will be a slight popping sound as the spring is released, [0068]
15. At the end of the freeze, release the trigger and it will lock
the push rod in place; for a more rapid defrost, squeeze the
trigger and retract the push rod to pull the CO.sub.2 snow back
away from the cap and release the trigger to lock the push rod, and
[0069] 16. After the defrost, squeeze the trigger to unlock the
push rod and pull the applicator out of the handle and drop the
push rod, spring, applicator, and its cap into a decontaminating,
chlorine solution.
[0070] For a cryotherapy process directed to the ablation of
cervical, precancerous lesions to prevent cervical cancer, and
utilizing what is called a "double freeze procedure," a second
freeze would be completed by completing steps 7 through 16 after a
five minute thaw cycle is completed and by using a second
applicator set (i.e., push rod, spring, applicator and its cap)
that would be provided with the device.
[0071] An alternative way to describe the method of the present
invention is note that it is a method for providing a patient with
cryotherapy ablation in which the steps for performing this method
utilizing a connection to the outlet of a pressurized tank of a
low-temperature liquid in association with the device as disclosed
in the prior paragraphs.
[0072] It can be seen that the current invention eliminates many of
the previously noted disadvantages (e.g., frequent tip blockages in
the very expensive, gold or chrome plated nozzles that do not hold
up well to frequently being disinfected; current devices on which
these nozzles are used cost around thirteen hundred dollars per
device; often considerable difficulty in maintaining such devices;
need to transport with these devices fifty pound tanks of carbon
dioxide tank; difficulty in scaling up the current process to
accommodate large numbers of patients) in traditional cryotherapy
processes.
[0073] It should be noted that many of the above-noted advancements
came about only after extensive trial-and-error efforts that
utilized a series of prototypes of the present invention. Each of
these prototypes also contained improvements and additional
features that were added to overcome some of the unexpected,
technical problems that were encountered in the operation of the
earlier prototypes.
[0074] For a first example, more recently the push rod or plunger
(60) of the present invention has had the base (66) on its distal
end (64) reconfigured so as to better control the rate at which the
applicator cap (50) warms up and detaches from the tissue when the
cryotherapy procedure is terminated. In earlier prototypes, the dry
ice that was at one time adjacent the push's rod's base would
occasionally move forward and maintain contact with the applicator
cap (50) even after the push rod itself had been locked or
retracted. This prevented the applicator cap from immediately
beginning to warm up when the cryotherapy procedure was
terminated.
[0075] To rectify this situation, a sand-anchor-shaped fitting or
anchor 61 was added to the push rod's base. See FIG. 4. This anchor
61 is configured to anchor the low-temperature, CO.sub.2 snow or
dry ice to the push rod. This anchor is seen to be cone shaped and
to have, on the cone's boundary surface 61a, laterally extending
ridges, fins or protrusions or threads 61b which provide more
surface area around which the snow can accumulate and that can be
used to further adhere the snow to the push rod's base.
[0076] For a second example, to make the snow collection process as
reliable as possible, it was found desirable to further evolve the
present invention's snow horn by improving upon the way that it
interfaces at its distal end with the piping assembly proximal end
and the way that it vents excess gases during the snow collection
process.
[0077] FIG. 5 shows a side view of the now modified, snow horn 26
of the present invention. It is seen to have at its distal end 26a
a snow horn nut 26d that is adapted to fit onto the piping
assembly's proximal end 22.
[0078] This nut includes a spring-loaded, pressure-relief collar or
other automatic, pressure relief means 26e that is adapted to open
at a specified pressure (e.g., approximately 90 psig) to allow
excess CO.sub.2 gases to be relieved before the pressure in the
snow horn rises to such a level as to threaten the actual rupturing
of the snow horn.
[0079] Notice should also be taken of the shape of the exterior
surfaces of the snow horn nut 26d and the snow horn collar 26e. The
have been specifically provided with complemental curvature or a
rounded interface 26g at the points where they contact each other
so as to enable the snow horn to be pivoted about these contact
points to aid in aligning the various components of the device
during the snow collection process.
[0080] For a third example, to make the tissue cooling portion of a
cryotherapy procedure as reliable as possible, it was found
desirable to further evolve the present invention's tubular
applicator by improving upon: (a) its consistency of performance in
allowing the collected quantity of snow to smoothly move forward
through the applicator without binding at various points on the
applicator's inner wall, and (b) its venting capabilities during
the snow collection process.
[0081] FIGS. 6 and 7 show, respectively, a side view and a
cross-sectional view of the now improved-upon, hollow tubular
applicator 30 of the present invention. The applicator's interior
wall 42 is unique because its diameter is seen to uniformly
increase from its proximal to its distal end (i.e., in the
direction of advancement of the collected snow during the cooling
portion of a cryotherapy procedure). For an applicator that has
approximate dimension of length=8 inches and outer diameter=3/4
inches, the amount of this increase is on the order 0.07 inches
with the interior wall having inside diameters of 0.425 and 0.490
inches at its respective proximal and distal ends. From our
experimentation, it appears that, in order to allow a collected
quantity of snow to smoothly move forward through the applicator
without binding at various points on the applicator's interior
wall, the angle of the spread of the interior surface of this wall
from its centerline needs to only be in the range of 0.1 to 0.5
degrees when the vent holes themselves have diameters in the range
of 0.015-0.030 inches. Alternatively, the amount of increase in the
interior wall's diameter between its ends when divided by the
length between these ends is in the range of 0.4 to 1.6 percent.
Although this taper is comparatively small, after much
experimentation with various prototype applicators, tapers of this
order of magnitude were found to be essential to allow for the
smooth advancement through the applicator of the collected snow
without it becoming bound at various points on the applicator's
interior.
[0082] The quantity and placement of vent holes 44 in the
applicator's wall was also, from extensive experimentation, found
to be important to the smooth advancement of the collected snow
through the applicator. Too many vent holes (e.g, approximately 400
vent holes with 0.02 inch diameters in a 12 inch long, 3/4 inch
outer diameter applicator) were found to cause too much surface
friction and impeded the smooth advancement of the collected snow
through the applicator. This decreases the performance of the
device by limiting how cold the applicator tip can get.
[0083] Venting of the now improved-upon, hollow tubular applicator
30 of the present invention is seen to be accomplished with an
assortment of vent holes whose number, locations and diameters are
a function of the mass of CO.sub.2 snow or dry ice that is to be
collected. For example, for an 8 inch long, 3/4 inch outer diameter
applicator that's to be used with approximately 12.5 grams of dry
ice, such an applicator would typically have: (a) 2 large diameter
vent holes that are located near its proximal end and allow
CO.sub.2 to vent into the device's handle, and (b) approximately
15-25 vent holes of 0.02 inch diameter that are located around the
perimeter of and near the center of the applicator. When only
approximately 10 grams of dry ice are to be used with this size
applicator, it would typically not have the centrally located vent
holes.
[0084] This improved-upon tubular applicator 30 is also seen to
have: (a) nub locks 46 near its proximal end that aid in locating
and locking the applicator into the device's handle 80, (b) coarse
threads on its distal end that are used to temporarily connect the
applicator to a snow horn during a snow collection process and to
the applicator during the freeze process, and (c) a finger grip 48
that aids in aligning the applicator to the device's handle and
temporarily locking the components together.
[0085] Another embodiment of this improved-upon tubular application
includes one that has double walls or tubes (inner and outer) that
are separated by an air gap that exists to provide the collected
snow within the applicator with insulation from its surrounding
hotter environment and to prevent the external surface of the
applicator from getting too cold. These tubes are not bonded
together so as to allow them to contract at different rates in
response to the exposure to extreme temperatures due to contact
with dry ice snow.
[0086] For a fourth example, much experimental effort has been
expended towards perfecting the design of the device's handle 80 so
as to maximize the reliability of its operation and its ease of
use. FIGS. 8-9 show respective right and left side, perspective
views of the handle of the present invention. It is seen to have on
its right side a wind knob 93 that one uses to wind a cable that is
connected to the base 66 of the push rod, and, when this cable is
wound onto a drum or spool 94, it causes the push rod to be
retracted out of the hollow, tubular applicator 30 into the handle
80 so as to make room in the applicator for the collection of a
desired quantity of snow and to compress the coiled spring 99 to
create the potential energy that is used to advance the dry ice
snalw. At the back, top end of the handle is a concave portion 95
in which sits a thumb-controlled, trigger button 97 that replaces
the index-finger activated trigger 90 that was used in the early
prototype handles. The center of this trigger button is essentially
in line with the centerline 96a or axis of the handle's barrel
96.
[0087] Extending downward and forward from the rear portion of the
handle's barrel is a grip 98 whose centerline 98a is oriented with
respect to the centerline 96a of the handle's barrel so as to be at
a specified included angle, .alpha., so as to optimize the
ergonomic advantages of the handle. From much experimentation with
early handle prototypes, it was found that an included angle in the
range of 10-20 degrees was preferred, with an included angle of
approximately 12 degrees being optimum.
[0088] FIG. 10 is a cross-sectional view of the handle's interior
and shows the drive and control system for controlling the push
rod's movement. The drum 94 onto which the cable is wound contains
a toothed, ratchet wheel 94a whose incremental movement occurs when
the thumb-controlled, trigger button 97 is pushed downward against
the resistance of a torsional spring and causes a link 94b to press
against the rachet wheel's paw causing it to disengage from the
ratchet wheel's teeth so as to release the potential energy of the
spring 99 and allow the base 66 of the push rod to apply the force
needed to advance the dry ice snow through the applicator.
[0089] The many features and advantages of the present invention
are apparent from the above detailed specification, and thus, it is
intended by the appended claims to cover all such features and
advantages of the invention which fall within the true spirit and
scope of the invention. Further, since numerous modifications and
variations will readily occur to those skilled in the art, it is
not desired to limit the invention to the exact construction and
operation illustrated and described, and accordingly, all suitable
modifications and equivalents may be resorted to and are considered
to fall within the scope of the present invention.
* * * * *